Another idea that might work, which is what I did in the same situation as you, (though in reverse, long story lol) when I flushed small plants and they took forever to dry out due to large pot size, is flush just the area around where the roots presumably are. E.g. start rinsing out and diluting the soil where the roots are, which means the soil will dry quicker and allow more repeated and frequent diluting/flushing till things are looking better.
Hmmm, sleepy so wasn't thinking too clearly, that probably won't help much in your position though.
I did it in reverse, e.g., I needed to administer nutes after a flushing that took forever to dry because of small plants in big pots, so as soon as I dared to, I began watering with nutes in just the area around the plant, while the outer edges of the soil continued to dry out.

My 2 cents.

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